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/**
 * Copyright (C) 2020 WaveMaker, Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 

 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.wavemaker.commons.io;

import java.io.InputStream;
import java.io.OutputStream;

import org.springframework.core.GenericTypeResolver;
import org.springframework.util.Assert;

import com.wavemaker.commons.MessageResource;
import com.wavemaker.commons.io.exception.ReadOnlyResourceException;
import com.wavemaker.commons.io.exception.ResourceDoesNotExistException;
import com.wavemaker.commons.util.WMIOUtils;

/**
 * Abstract base class for read-only {@link File} implementations that are not contained in any {@link #getParent()
 * parent} {@link Folder}.
 * 
 * @author Phillip Webb
 */
public abstract class AbstractReadOnlyFile implements File {

    private final FileContent content = new AbstractFileContent() {

        @Override
        public OutputStream asOutputStream() {
            throw newReadOnlyResourceException();
        }

        @Override
        public OutputStream asOutputStream(boolean append) {
            throw newReadOnlyResourceException();
        }


        @Override
        public InputStream asInputStream() {
            InputStream inputStream = getInputStream();
            if (inputStream == null) {
                throw new ResourceDoesNotExistException(AbstractReadOnlyFile.this);
            }
            return inputStream;
        }
    };

    @Override
    public Folder getParent() {
        throw new UnsupportedOperationException();
    }

    @Override
    public void delete() {
        throw newReadOnlyResourceException();
    }

    @Override
    public boolean exists() {
        InputStream inputStream = getInputStream();
        try {
            return inputStream != null;
        } finally {
            WMIOUtils.closeSilently(inputStream);
        }
    }

    @Override
    public void createIfMissing() {
        throw newReadOnlyResourceException();
    }

    @Override
    public String toString() {
        return toString(ResourceStringFormat.FULL);
    }

    @Override
    public File moveTo(Folder folder) {
        throw newReadOnlyResourceException();
    }

    @Override
    public File copyTo(Folder folder) {
        File file = folder.getFile(getName());
        file.getContent().write(this);
        return file;
    }

    @Override
    public File rename(String name) {
        throw newReadOnlyResourceException();
    }

    @Override
    public void touch() {
        throw newReadOnlyResourceException();
    }

    @Override
    public long getSize() {
        return 0;
    }

    @Override
    public long getLastModified() {
        return 0;
    }

    @Override
    public FileContent getContent() {
        return this.content;
    }

    @Override
    @SuppressWarnings("unchecked")
    public > O performOperation(O operation) {
        Class typeArgument = GenericTypeResolver.resolveTypeArgument(operation.getClass(), ResourceOperation.class);
        Assert.isInstanceOf(typeArgument, this);
        operation.perform((R) this);
        return operation;
    }

    @Override
    public int hashCode() {
        return toString().hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        return toString().equals(obj.toString());
    }

    /**
     * Return the input stream for the contents of the File or null if the file does not exist.
     * 
     * @return the {@link InputStream} or null
     */
    protected abstract InputStream getInputStream();

    /**
     * Return the {@link ReadOnlyResourceException} that should be thrown on error.
     * 
     * @return the exception
     */
    protected ReadOnlyResourceException newReadOnlyResourceException() {
        return new ReadOnlyResourceException(MessageResource.create("com.wavemaker.commons.read.only.resource"), toString());
    }
}